Tobacco sheet is a reconstituted tobacco made via re-composing and processing by using tobacco wastes as raw materials, such as tobacco dust, stem, leaf-scrap and some parts of low-grade tobacco-leaf formed during cigarette manufacture process. First, it can utilize raw leaf materials as many as possible to save cigarette cost; second, tobacco sheet has important role in reducing tar release and minimizing cigarette harm. Currently, papermaking process is the one most widely used in the tobacco sheet production. Physical performances of the tobacco sheet made by papermaking process are much better than that made by slurry process, which can effectively reduce tar and harm in cigarette smoke.
Generally, preparation method of papermaking process tobacco sheet includes steps as follows: to immerge and to extract tobacco materials (stem and leaf-scrap) by hot water; to separate tobacco's water-soluble matters from insoluble materials such as tobacco's fiber and etc. via solid-liquid separation process; to put the separated fibers on papermaker machine to shape flake base, and to distill and to concentrate the water-soluble matters to obtain tobacco extract; to immerge or to spray the flake base by the extract; finally to dry the extract-coated flake base to obtain the tobacco sheet.
There are many methods for producing papermaking tobacco sheet in the current technologies, but improvements released by current technologies for tobacco sheet production methods have been mainly focused on how to treat production materials of the sheet.
There is an extraction process of leaf scrap in current production methods for papermaking tobacco sheet. Because efficiency of the extraction is lower, tobacco flavor ingredients resided in the leaf scrap lose during long sequential process, resulting in the papermaking tobacco sheet with worse inherent quality, heavy stemy taste, insipid smoke and even less.
In other hand, because the papermaking tobacco sheet is produced by the tobacco stem and leaf scrap (over 2 mm) as its raw material, some parts of tobacco are not effectively utilized, such as the tobacco dust in diameters of 2 mm-100 mesh formed in cigarette process, or low-grade tobacco leaf, or scrap that is produced in threshing and redrying process and is difficult to be used in the sequential process of current cigarette manufacture, therefore, the raw material resource is wasted.